robertson



DEC- 9 H. M. ROBERTSON COMBINATION OPEN AND MUFFLE KILN AND METHOD OF OPERATING THE SAME Filed Dec. 11, 1920 3 Sheets-Sheet 1 INVENTOR /LM1 ATTORNEY Dec, 30, 1 924.

H. M. ROBERTSON NATION OPEN ANT) MUFFLE KILN AND METHOD OF OPERATING THE SAME CDMBI Filed Dec. 11 1920 3 Sheets-Sheet 2 bec, 30, 1924.

H. M. ROBERTSON COMBINATION OPEN AN MUFFLE KILN AND METHOD OF OPERATING THE SAME Filed Dec. 11, 1920 I5 Sheets-Sheet 1 (NVENTDR /m ATTORNEY Patented Dec. 30. 1924.

UNITED STATES HARRY M. ROBERTSON, OF CLEVELAND,

1,521,392; PATENT OFFICE.

OHIO, ASSIGNO'R no Aitt itifioAN nitrssLnit TUNNEL KILNS, INC., or NEW YORK, N. Y., A conPoRAr'ioN or COMBINATION OPEN AND MUFFLE KILN AND METHOD nearest-arms SAME.

Application filed December 'lo till-whom it may concern:

Be it known that I, HARRY M. Ronmrrsong a citizen of the United States, and resi-, dent of Cleveland, in the county of Cuyahoga and State of Ohio, have invented certain new and useful Improvements in Com- ."bination Open' and Mufile Kilns and Methods of Operating the Same, of which the following is a specification.

The general object of my present invention is to provide a'novel and etfective contiuuous tunnel kiln'especially adapted for usein burning and flashing or salt glazingbrick, drain tile and analogous ceramic ,ware.

' More specifically the object of my invention is a kiln having novel and effective provisions for obtaining the desired temperature graduations along thev length of the'kiln chamber and the maintenance of the proper flashing, glazing or other special atmosphere required in a high temperature zone of the kiln intermediate the heating up and cooling zones or ends of the kiln. T In carrying out my invention I supply heat to said intermediate k-iln zone by passing burning gasesaud hot products of coinhnstion through the goods receiving space in this portion of the kilrf'chamber, and heat the heatin up zone portion of the kiln by means of IIIHEQS or combustion chambers through which flow burning gases or hot products ,of combustion. I am thus enabled to main-- tain an atmosphere i'n the goods receiving zone of this portion of the kiln which is independent of the character of the gases passing through the inufiles or combustion chambers. Advantageou'sly and preferably the combustion chambers or muflles are of the well known hollow wall type emp oyerl in the ordinaryv Dressler tunnel kilns.

The various fear-tires of novelty which characterize inyinv cntion are pointed .out with particularity in the claims annexed to and forming a part of this specification. Fora better understanding of the inven i'ion however. of the advantages possessed. y it, and specific advantages attained with. it. reference should be had to the accounpanying drawings and descriptive -matter in which I have illustrated and described. preferred forms of apparatus.

IF the drawings:

Fig. l is a somewhat diagrammatic plan view partly in section;

' ing D";

11, 1925. serial m. amen Fig. 2 is a partial section elevation taken on the broken line 22 of Fig. 1; K

F lgs. 3, 4 and dare transverse sections taken respectively on lines t i, and

55 of Fig. 1;

F ig. 6 is a partial section takenon the "mediate high temperature zone A. The

goods treated in the kiln are moved slowly through the latter onflca'rs B running on track rails B, the cars entering, the kiln at the preheating end of the latter andleaving the kiln at the cooling end.

To heat the kiln I employ furnaces, C, of which 12 are showin'arranged six at each side of the kiln in a series'ru nning the length of the furnace zone A of the kiln. Advantageously, as shown, eacll of the furnaces C is of the so-calledfurnace gas producer ,tyipe and comprises a chamber having rcfractoi'y walls irito which solid fuel, as coal or coke,'is passedas required tlirouuh a hole C n ormallywlosedby a door. (1 At its inner side'each furnace]chamber'is open to the kiln chamber at 0*. At the bottom of each furnace chamber is provided a grate D, which, as shown, is of a known type made of cast iron u'lthftrunnitni supand 6 but may be swung'into the position shown in dotted lines in F ig. 6, to dump the furnace contents iutothe ash pit Cf provided beneath each furnace chamber; 'lhe'o uter trunnion I) of each grate I) is hollow and open at its outer bud. In operation, atmospheric air is drawn into each hollow grate through its trunnion D. by the kiln draft supplemented by the injector action of a steam nozzle- I) dis charging axiallyinto, the hollow trunnion D and receiving steam from a supply pip- Each grate .l) is formed with an air and steam outlet. I) at its upper side and is provided with a hood D preventing fuel and ashes from passing into the hollow space'in the furnace zone section of the kiln and the furnace outlets C at each side of the kiln is a corresponding bafile wall F which extends nearly, but not quite to the roof of the kiln chamber, and advantageous 1y has its outer side inclined as shown in Big. 4 to deflect the burning gases entering.

the kiln chamber through the furnace outlets C to ,the top of the kiln chamber. Ordinarily and preferably, ports F are formed in theupper portionv of each wall.

F. Advantag'eous y for structural reasons and to restrict the flow of burning gases longitudinally of the 'kiln in the furnace zone portion of the latter, transverse walls G are provided as shown at intervals across the space between the outer side of each baflle wall F and the adjacent kiln wall. As shown the walls G are arranged one between'each adjacent pair of furnaces C and extend to the roof of the kiln chamber proper.

. Located in the base of each wall F is a conduit H running longitudinally of the passa es H open into each conduit H at interva along its len th from the goods receiving space of theiiln. Thepassages H open to the kiln clfizgmber' proper adjacent the level of the goo supporting platforms of the cars B, and prefera H into the conduits/H issue from the. lather into m ufiles or conduits J ,which extend longitudinally of the kiln chamber through the reheating zone A 'thereofq and communicate at the end of-the kiln through rts K and a'tunnel K with la suitable raft creating device shown as He stack K.

The walls of the conduits J are preferably formed as shown 'of hollow tile sections, the passages J in which form channels for the circulation of the kiln atmosphere as indicated by the arrows in Fig-. 5. The conduits H are thus of the same construction and perform the same kiln heating and temperature equalizing functions as the so-called combustion chambers commonly employed in the continuous tunnel kilns of the well known Dressler type. To regulate the kiln draft the conduits H may each be provided with a damper H Advantageously the conduits or mufl'les J extend only something like ly so as to regis-.- ter with the transverse channels B which are formed in the car bodies and are open halfway from the benches A on which they rest to the top of the kiln chamber. To restrict undesirable longitudinal flow of the kiln atmosphere from the furnace zone A of the kiln chamber into the preheating zone A, I provide baliles I which project out wardly from the combustion chambers and depend from the root of the kiln chamber into proximity with the space traversed by the goods mounted on the goods carrying cars B.

The cooling zone A of the kilnis formed with double side and roof walls so that in effect it comprisestwo tunnels, one within the other. vAtmospheric air is allowed to pass into the chambers L between the double side walls of the cooling zone through ports L formed in the outer wall. These ports may be throttled more or less by dampers or brick forming throttling devices L. Passages L are formed in the inner side walls of the cooling zone through which air may ass into the kiln chamber from the cham or L. The passages L may be wholly or partially closed by bricks L which can be adjusted through the ports L. The ports L and L are advantageously distributed along. the length of th cooling zone. The chambers L communicate at their upper dgcs with the chamber M between the doule roof wallsof the cooling zone portion A of the kiln. The chan'iber M is connect-. td adj acent tliejunction of the zones A and A to vertical conduits 0 one at each sidev a fan N, through the supply connectign N or may receive air at atmospheric iessure through the pipes N and N. s own in Fig. 1 provisions are made for using the heated air issuing from-the pipes N in whole or in part as the secondary air a! combustion for the furnace 'C. Theair th used asses from the tunnels or conduits i or to which the, pipes N discharge, into piping P provided with a branch con ection P to each furnace chamber, These bi anch connections are each controlled by individual valves P. and as shown, each enters the corresponding .furnace chamber through-the wall portion between the openings C and 'C. The conduits K and K arealso connected to the stacks K and KA. respectively, and each ining the pipes N ieitlier directly to the at mosphei-eni-rougn the ranch pipes or through the fan N according to the mode of open and that thoralves P" are open and dampers K are wholly or artially closed, the operation of the apparatus shown in Figs. 1-36 is as follows: p 7

Primary air-passes into the bottom of each furnace chaniberC tli rough tl to corresponding equalize the temperatures at all points in any transverse vertical plane through the kiln chamber. Exactly the same downfiow of the kiln atmosphere and resultant heat equaliz- 7 ing effect is obtained in the high tempera- 'ture open fire portion o f my'improved kiln with the special arrangement of furnace chambers'C, bafile walls F and outlet connections H shown. T he withdrawal of the burning ases from the kiln chamber through t e outlet passages H 'from' the high temperature zone A tends to cause air leaking into the kiln at'its entrance end or hollow grate D under the draft due to the .into the cooling zone of the kiln to flow stack K which may be supplemented by the injector actian f the steam jets discharged by the nozzles E.- The combustible gas gen erated by the passage otrhesream and air into the fuel bed in each erases C unites in combustion as itrises fromthfe fuelbed with the secondary air sup lied tli'iongli the pipes P 'The burning an burnt gasespass from 'eaeh combustion chamber through the corresponding outlet G into the. kiln chamber proper and are diverted toward the top .of the kiln chamber by the-adjacent baffle wall F. The bulk-of'the burnt and burning gases passes into the goods receiving.

portion of the kiln ch'an'iber over thetops oi the walls F but a portion of these gases passvs through the ports F.. From the up: per port ion of the kilnchainlmr the gases pass downward along and through the a mess between the goods on thefcars ll to t'e platforms of the latter, and into the chanmzrlaB in the car platforms and thence passe into the conduits H through the passages H. From the conduits H the gases pass into the lnuiiios or combustion chainhers J und finally pass from the latter into the stack K. Innormal operation the major portion of the available heatin theburning gases passing into-the kiln chamber from the furnace chambers G is retained byfthe. gases when they cnterthe combustion chamber or muilles J} and istran'smitted to the goods in the heating up zone of the kiln. 'lhetempera-v lure of the heating up zonerises gradually fronrthe end of the kiln to the high temeraturc zone A'fl und the transfer of heat from the, muillcs or combustion chambers J to the goods in the heating up zone is mainly effected by convection currents of the kiln atmosphere as in the ordinary Dressler kiln, these convection currents passing through and being directed by the open ended chain through the goods receiving space of the .-kiln \VlllCll is characteristic oi -l he coloration of an ordinary Dressler kiln, has a highly desirable and well recognized tendency to from the end portions of the kiln into the zone. A, and prevents any appreciable flow of the. gases from the zone 'A' of the kiln into theotherkiln zones. This is espegially important in the case of the heating up zone A; wherein it is, in general, desirable to maintain a highly oxidizing atmosphere. while in the zone A. the atmosphere -should in general, be either neutral or reducing in I order to secure a flashing or salt glazing cfi'ect. Whether the atmosphere in the zone A is reducing,'neutral or'oxidizing, depends on the relative amounts of secondary air supplied to the pipes PF, and is controlled by the valves P, which are opened to make the atmosphere oxidizing andlthrottled to make it reducing. Whensalt glazing is desired the salt is vaporized in the furnace chambers .G into which it may be fed inany suitable manner as, for instancej'by mixing it with the coal thrown from tiineto time. on the tops of the fuel beds in'tlie furnace chambers. The special-producer 'furnace construction employed is not of itself novel with me exceptin the special relation in which I employ it, but'on'the contrary is of atype which has been foundh'i'ghly desir able because of the eiiiciency of the 1 com-- bustion obtainable and the-relatively-small labor cost of '0" eration'.

While I consider it generally dosirablet. o'

increase the eiliciency of the apparatus by using asthc secondary air, preheated .air, withdrawn from the truck cooling pipes N as shown or from other cooling apparatus of the kiln. the latter will operate satisfactorily with unheated secondary air" drawn into the furnace chzimbeniuhnel from-the a-tlnosphere by the kiln draft. suction. When it is desired to operate the apparatus shown in Figs. 1 to (i in this manner, the valves N are manipulated to connect the pipes N to the atmosphere through the pipes N and the valves 1 are closed. Secondary air may then be admitted to the'furn'ace chambers (7 through the openings C". by" opening the doors or cover plate C, or by opening damp- (511* normallyclosing'openlngs C? in said plied to the chambers thus withdrawn ma and ruggedness m construction,- and'forms the kiln- 'lheamount' of air permitted to pass into the kiln chamber proper from the ports L depends, in genera upon the character. ofi'goods being handled. With finer and-more delicate ware little or no air should pass into-the kiln chamber-through the ports L while with coarser, stronger ware considerable quantities of air may advantageously be introduced.

By properly adjusting the dampers K controlling the suction effects of the two stacks K and KA or other draft producing devices, the kiln may be operated without any appreciable longitudinal flow of thekiln atmosphere from one of the zones 'A and A, into the otherveven though the ports L, are wide open the full length of the-cooling zone A It will be understood, of course, that the hot airwithdrawn from the hollow walls of the cooling zone section of the kiln or 'from the truck cooling pipes N can be advantageouslyused in driers or for analogous purposes in many cases.

The modified form of apparatus shown in Fig. 7 differs from; that shown in Figs. 1 to 6, primarily in that the conduits H are connected directly to a stack KB, and the combustion chambers JA in the preheating zone of the kiln are heated by combustion occurring in those chambers of, fuel gas and air for its combustion which may be supplied to the chambers in any suitable or usual manner. As shown fuel gas is sup- J A through conduits Q from producers Q, supplying air to the chambers JA. is illust rated'and none needbe described as this air and, indeed the fuel gas may be supplied in any of the known ways such as are commonly employed for example in ordinary Dressler kilns. As shown air is withdrawn from the cooling zone A of the kiln bya fan R connected to the tunnel P. The heated air be utilized in the various ways in whic the hot air from the cooling zone of an ordinary kiln is ordinarily utilized, With the construction shown in Fig. 7 ordinarily but one or two furnaces 'C at eachside of the-kiln are required to obtain a flashing or salt. glazing effect. The same kiln atmosphere and the same kiln atmosphere circulation can be had with the construction shown in Fig. 7 as with the construction first described.

Having now described my invention, what I claim'as new and desirc to secure by Letters Patent, is:

1. The method of. treating ceramic ware which consists in gradually heating the ware to a high temperature by passing the ware through a continuous tunnel kiln comprising a heating up zone in which the ware rebut no provision for ceives the major portion of its heating and in which an oxidizing atmosphere is maintained, and a successive kiln zone in which further heat is supplied to the were and the latter is subjected to a non-oxidizing atmosphere by contact-with hot gases passed into the kiln chamber at its top and withdrawn from the kiln chamber at its bottom.,

2. The method of operating a continuous tunnel 'kiln which consists in passing hot furnace gases into the kiln chamber at the top of a high temperature zone thereof and withdrawing them from the kiln chamber at. the bottom of saidzone while still retaining the major portion of their available heat and then passing the gases through conduits or muflles in an adjacent elongated heating up zone of the kiln to thereby transmit thev remainder of the ava able heat in the gases to goodsv assing fisst through the preheating zone-and then through said high temperature zoneof the' kiln.

3. The combination in a continuous tunnel kiln, of an elongated heating up section, an adjacent shorter hi h temperature section, and heating means or the kiln comprising provisions for passing burning gases into current circulation of the kiln atmosphere upward past said chambers and downward through thego'ods pathway.

4. The combination in a continuous tunnel kiln, of an elongated heating up section, an adjacent shorter hi h temperature section, and heating means or the kiln comprising provisions for passing burning gases into said hi" h temperature kiln section at its top and withdrawing the heating gases from that section at its bottom, chambers in the heating up section of the kiln arranged at the sides of the goods pathway therethrough,

provisions for passing the heating gases withdrawn from the high temperature section through said chambers, and provisions for directing'a convection current circulatiouof the kiln atmosphere upward past said chambers and downward through the goods pathway.

5. In a continuous tunnel kiln comprisup section and an ad acent"- open fire heated section. the combination of 1 ing a heating furnaces at the sides of the open fire heated section, walls interposed between the turnaccs and the goods receiving space of the kiln for causing thefurnace gases-to pass into the goods receiving space at the top of the latter, conduits formed in said walls and communicating with the goods receiving space adjacent the bottom of the latter for withdrawing furnace gases from the kiln chamber, internally heated chambers arranged in the heating up section of the kiln at the opposite sides of the goods receiving space, and baflles fitting snugly about the space traversed by the goods adjacent the inaction of the two kiln sections to restrict ongitudinal flow of the kiln atmosphere from one section into the other.

6. In a continuous tunnel kiln comprising a heating up section and an adjacent open fire heated section, the combination of furnaces at the sides of the open fire heated section and walls interposed between the furnaces and the goods receiving space of the ill kiln for causing the furnace gases to pass into the goods receiving space at the top of the latter, conduits formed in said walls and commuicating with the goods receiving space adjacent the bottom of the latter, and muflles or heating chambers arranged in the heating passages up section of the kiln at the opposite sides of the goods receiving space and communieating with said conduits at the junction of said kiln sections, draft provisions for causing heating gases to pass out of the kiln chamber into said conduits and thence throu h said chambers.

7. n a continuous tunnel kiln for first heating and then cooling goods, passin through the kiln, the improvement whic consists in a cooling zone section formed with air chambers in its walls and regulable air kiln and connecting the air chambers b0 the atmosphere, and also to the interior of the kiln chamber, and means for causing a longitudinal flow through the air chambers toward the hot end of the cooling zone sec tion.

Signed at Cleveland, in the county of Cuyahoga and State of Ohio, this 9th day of December, A. D. 1920.

HARRY M. ROBERTSON.

distributed along the length of the 

